Albumin reprograms the B cell transcriptional landscape and improves neutrophil antimicrobial function in patients with decompensated cirrhosis

Abstract

Background&AimPatients with acutely decompensated (AD) cirrhosis are immunocompromised and particularly susceptible to infections. This study investigated the immunomodulatory actions of albumin by which this protein may lower the incidence of infections. MethodsBlood immunophenotyping was performed in 11 AD patients and 10 healthy volunteers (HV). Bulk and single-cell (sc) RNA sequencing (RNA-seq) and flow cytometry were performed in peripheral blood mononuclear cells (PBMCs) from 20 AD patients and 34 HV exposed to albumin. Albumin’s effects on degranulation, phagocytosis, chemotaxis, and swarming of neutrophils from 6 AD patients and 9 HV were assessed by myeloperoxidase enzymatic activity, engulfment of fluorescent-labeled Escherichia coli and zymosan and interactions at single-cell resolution of neutrophils with Candida albicans in microfluidic chambers, respectively. Whole blood RNA-seq analyses were performed in 45 patients admitted for severe AD of whom 30 received albumin during hospitalization. ResultsCompared to HV, AD patients showed severe lymphopenia and defective neutrophil anti-microbial function. Bulk and scRNA-seq analyses revealed significantly (false discovery rate (FDR)<0.05) increased signatures related to B cells, myeloid cells and CD4+ T cells in PBMCs incubated with albumin. Changes in the B cell population were confirmed by flow cytometry. Neutrophils exposed to albumin also exhibited augmented chemotactic and degranulation responses, enhanced phagocytosis, and increased pathogen-restrictive swarming. Analysis of RNA-seq data in patients who had received albumin revealed specific upregulation of signatures related to B cells and neutrophils together with transcriptional changes in CD4+ T cells (FDR<0.05). ConclusionsThe finding that albumin promotes the transcriptional reprogramming and expansion of the B cell compartment and improves neutrophil antimicrobial functions indicates mechanisms that may lower the incidence of infections in patients with severe AD receiving albumin therapy.